The present invention relates to a process for forming a color image with a silver halide color photosensitive material. In particular, the present invention relates to a process for easily forming a color image without necessitating a desilverization step.
Various processes have been known for forming a color photographic image. Among them, a process wherein a silver halide emulsion is used and the development is conducted with a developer containing an aromatic primary amino color developing agent in the presence of a color coupler is usually employed. In this process, a desilverization step wherein developed silver formed together with a dye in a color development step is removed is necessitated, since the silver thus formed is usually black and impairs the color tone. The desilverization step comprises a step of bleaching the developed silver (bleaching step) and a step of removing undeveloped silver and bleached silver (fixing step). Therefore, the color photograph is prepared by the following treatment steps: ##STR1##
Recent advances in color photography have led to a strong need for, simplification of the treatment steps and reduction of treatment time. Various efforts have been made to improve both the solutions for treating photosensitive materials and the processing equipment. As a result, elimination of the intermediate step of washing with water and the desilverization step has been made possible. At present, a so-called bleach-fixing step wherein both bleaching and fixing are conducted in one step is practically employed. The most simplified color paper is treated at present by the following steps: EQU development.fwdarw.bleach-fixing.fwdarw.washing with water or stabilization.
Now, a further simplification of the process is desired. For further simplifying the process, a process wherein the development and desilverization are conducted in one step or a process wherein the step of washing with water or stabilization is omitted is possible. However, these processes are difficult and they have not been practically employed. Particularly the process wherein the development and desilverization are conducted in one step is quite difficult, since the development (a reduction reaction) must be conducted simultaneously with the bleaching (an oxidation reaction).
Several processes have been proposed for conducting the development and desilverization in one step. On pages 33 to 37 of Nippon Shashin Gakkai-shi, Vol. 21, No. 3 (1958), a mono-bath processing of a color film is reported. In this process, a positive color film is developed, fixed and desilvered (bleach-fixed) in one bath. It is also described therein that the processing solution has only a very short shelf life, that it generates ammonia gas and that it becomes turbid. It is quite difficult to use such a solution on an industrial scale and it has not been used in practice, though investigation thereof is interesting. U.S. Pat. No. 3,923,511 discloses the development/bleaching/fixing process for a photographic material with a single bath of aqueous alkali solution containing a developer, cobalt (11) complex and a solvent for the silver halide, and Japanese Patent Unexamined Published Application (hereinafter referred to as `J. P. KOKAI`) Nos. 49-54034 and 54-161333 also disclose the development/bleach/fixing process for a photosensitive material containing a developing assistant. Also this process has a defect of unstability of the processing solution. J. P. KOKAI Nos. 56-109346 and 61-77851 and Japanese Patent Publication for Opposition Purpose (hereinafter referred to as `J. P. KOKOKU`) No. 61-15422 disclose and intensification process. It is described therein that the desilverization process can be omitted, since a large amount of silver is not necessitated. However, this process also has not been employed in practice, since the solution is unstable like the solution used for the development/bleach/fixing and the compounds used are not sufficiently safe. J. P. KOKAI No. 54-137332 discloses that a photoprophic material comprising ferric or cobalt (II) complex salt of anionic polymer latex impregnated with a coupler is subjected to the development/fixing treatment in a single bath, i.e., a photosensitive material containing a bleaching agent is developed and fixed. Although this process is free from the problem of the instability of the processing solution, it has another problem that the stability of the photosensitive material is insufficient due to an interaction between the emulsion and bleaching agent.
J. P. KOKAI No. 54-137332 also describes, for comparison, the development and fixing of a color paper containing a silver chlorobromide emulsion and a coupler. The above-described Nippon Shashin Gakkai-shi, Vol. 21, No. 3 also discloses the development and fixing of color papers and color positive films available on the market at that time. However, problems such as unclear colors and prolongation of the development time remain unsolved.
U.S. Pat. No. 4,216,285 further discloses that when a movie color positive film (Eastman Color Print Film, type 5381 and type 7383) is processed with a single solution for the development and fixing with the pH and concentration of a solvent for silver halide contained in the solution maintained within a predetermined range, the covering power of the thus formed developed silver is low, so that its effect on unclear color of color image is reduced and simultaneously the developed silver remains. Thereby, a good image and photosoundtrack can be formed without employing any special process. However, problems such as unclear colors and prolongation of the development time remain unsolved.